Disk cartridges have been configured, for example, as shown in FIG. 44. Referring to this figure, there is shown a related art disk cartridge 101 in which a disk D such as a DVR, DVD, or DVD-ROM is rotatably housed between upper and lower shells 102 and 103. In this disk cartridge, a pair of upper and lower pickup insertion ports 104, which are formed in the upper and lower shells 102 and 103 respectively, are opened/closed from the upper side of the upper and lower shells 102 and 103 by a shutter 105 having a nearly U-shape in cross-section, and the shutter 105 is slid along one side surface 101a of the disk cartridge 101.
The related art disk cartridge 101, however, has a problem that since the shutter 105 is mounted to the outer side of the disk cartridge 1, the shutter 105 is simply openable by sliding the shutter 105, to allow damage of the disk D in the disk cartridge 101 or adhesion of dust or the like on the disk D, thereby causing drop out of data at the time of recording and/or reproduction of the data.
To solve the above problem, the present invention has been made, and an object of the present invention is to provide a disk drive unit using a disk cartridge which houses a disk-like recording medium and which is configured such that a pickup insertion port is opened/closed, from inside, with a shutter by rotation of an inner rotor, characterized by reasonably, smoothly opening/closing the shutter by rotation of the inner rotor.